1. Field of the Invention
The present invention relates to a processing method for selectively processing a film to be exposed formed on a substrate, manufacturing method of a semiconductor device, and processing apparatus.
2. Description of the Related Art
In general, with advance of semiconductor element miniaturization, it has become essential to enhance precision of an alignment technique with a lower layer in a lithography process. To align a pattern already formed on a substrate with a pattern to be exposed at exposing latent image, an exclusive scope for detecting an alignment mark position has heretofore been used. However, since an offset surely exists between the exclusive scope for alignment and exposure axis in this method, a deviation is generated between the alignment scope and exposure axis because of an influence of thermal drift, and an alignment deviation of the alignment mark position is generated. Therefore, with the advance of the miniaturization of a semiconductor, a problem has occurred that magnitude of the alignment deviation of the alignment position largely influences yield of a chip.
To improve this, an exposure-through-the-reticle (ETTR) method of detecting alignment mark and exposing pattern along the same axis is considered as a promising alignment technique of the next generation. In the ETTR method, high-precision alignment can be realized. On the other hand, since light source with same wavelength of a DUV region as that of the exposure is used, light absorption is large in an anti-reflection film formed below a resist layer. A problem occurs that position information cannot be detected from the alignment mark in the anti-reflection film lower layer. Similarly, when the films formed on the alignment mark such as an organic insulating film and interlayer insulating film of SiN or SiC is opaque to an exposure light, position information of the alignment mark cannot be detected. Moreover, even when the alignment by ETTR is not performed, and even when contrast of an alignment light is weak, position information of alignment cannot be detected.
To solve the problem, there has been proposed a method of selectively remove the opaque film formed on the alignment mark with laser ablation before an alignment step. However, this method has a problem that particles generated at a laser ablation sticks to a device pattern region, which forms a critical defect.